A technology for joining an instrument panel reinforcement to a cowl in a vehicle front-rear direction with a cowl-to-brace at the driver seat side is disclosed in the below-mentioned Patent Reference 1 (Japanese Patent Application Laid-Open (JP-A) No. 2008-114645). Describing this briefly, the instrument panel reinforcement is a high-strength pipe-form member joining left and right front pillars. The cowl is a gutter-form member disposed to the vehicle forward side of the instrument panel reinforcement. The cowl-to-brace is formed as an arm, of which a forward end portion is fixed to a rear end portion of the cowl, and a rear end portion of the cowl-to-brace is fixed to the instrument panel reinforcement. Thus, the instrument panel reinforcement and the cowl are joined in the vehicle front-rear direction.
Patent Reference 2 (JP-A No. H10-129520) discloses a technology in which an instrument panel reinforcement and a dash panel are joined by dash braces that extend in the vehicle front-rear direction, at both the driver seat side and the passenger seat side.
The above-mentioned cowl-to-brace and dash braces are provided for the purpose of reducing booming noise, which is one of the types of noise in a vehicle cabin, and the like.    Patent Reference 1: JP-A No. 2008-114645    Patent Reference 2: JP-A No. H10-129520